Progress in FY2009 was in the following areas: (1) INITIAL STUDIES OF HIV-1 CAPSID ASSEMBLIES. We have carried out the first solid state NMR studies of supramolecular assemblies formed by the HIV-1 capsid (CA) protein. CA comprises the conical capsid shells within mature HIV-1 virions. By itself, recombinant CA assembles into tubular structures (at high ionic strength) and other structures, all of which are believed to have the hexagonal arrays of CA molecules that occur in the intact virion capsids. We have shown that good quality solid state NMR data can be obtained from tubular CA assemblies, with isotopic labeling of the CA protein. Analysis of the data obtained to date indicates that CA retains its helical N-terminal and C-terminal domain structures (previously determined separately and in non-assembled form by solution NMR and crystallography) in the assembled state, and that nearly the entire protein becomes immobilized. Tentative assignments of numerous NMR signals have been obtained from our initial data, setting the stage for experiments that will provide constraints on the full molecular structure of hexagonal arrays of CA molecules. (2) DETERMINATION OF HELICAL BUNDLE STRUCTURES FOR HIV-1 VPU. We have completed and analyzed a series of solid state NMR measurements on the transmembrane domain of the Vpu protein, which is capable of forming oligomeric ion channels that may be related to Vpu's role in viral budding. Our data provide constraints on the supramolecular structure of symmetric helical bundles that may represent the ion channel-active state of Vpu. Solid state NMR measurements have been supplemented by photochemical crosslinking and analytical ultracentrifugation studies to determine the oligomerization number. Although our data indicate a diversity of oligomerization states for Vpu in phospholipid bilayers, the predominant oligomer appears to be a pentamer. We have developed specific models that are consistent with existing data through computational modeling and energy minimization. Papers describing our CA and Vpu results are currently in preparation.